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Ethanol-run diesel buses in Stockholm
N3
nitride products on $21.9 million. The biggest application sector, ceramic wear parts, is set to grow from $218 million in 1991 to over $300 million in 1995. The highest growth rate, however, will be seen in the automotive catalyst support market, boosted by EC legislation on car exhaust emissions, which is expected to grow by over 18% to be worth $240 million in 1995. Legislation protecting against air pollution, already vigorously pursued in Germany, The Netherlands, Austria, Switzerland and Scandinavia has also boosted the catalyst supports market and even the industrial emissions sector, which experienced a large fall during 1990, is forecast year on year growth through to 1996. Within the automotive sector, several other ceramic applications are also expected to grow significantly up to 1995. “Although it is not unanimous,” Frost & Sullivan say, “it is expected that the use of silicon nitride parts and possibly valves in turbochargers may have become important in a series of production cars by 1995, with the lead given by German producers or UK-based Japanese producers.” The market for ceramic membranes, dominated by French producers in applications ranging from food and drink production to effluent cleaning, is expected to grow to more than double its present size by 1995. Other application sectors forecast to grow in coming years are cutting tools, bioceramics and molten metal filters used in high-temperature processes. The biggest national market is Germany due to lts high investment in pollution control technology and itsvery large dynamic mechanical and process engineering sectors. It is also the largest net exporter of engineering ceramics to other European countries. The
applied catalysis A: General
other main national markets are France, the UK and Italy. For further information, contact Nick Betts at Frost & Sullivan Ltd., Sullivan House, 4 Grosvenor Gardens, London SW1 OHD, UK, or Anne Gilroy at Frost & Sullivan Inc., 106 Fulton Street, New York, NY 10038, USA.
Ethanol-run Diesel Buses in Stockholm
A major road test has been going on for nearly two years in Stockholm city traffic with a fleet of 32 diesel buses run on ethanol. The aims of this test are: (a) to establish the real costs of operating a bus fleet on ethanol and to evaluate techniques and infm-structure; (b) to check exhaust emissions, both unregulated and regulated; and (c) to develop the engine system and produce a fuel specification. The ethanol (959/o,with 5% water) used is produced from a waste liquor from paper manufacture at a paper mill in the north of Sweden. A blend is made there of this ethanol (95%) MTBE as a denaturing agent (2%) and Avocet ignition enhancer (3%); this blended fuel is then transported by a truck to the bus depot, 700 km to the south. The Saab-Scania diesel bus engines have been modified, with the combustion chamber, compression, injection pressure, injection timing, etc., all adapted to the new fuel. The passenger load of the buses is 36 seated and 43 standing. The buses have been testing two exhaust catalysts: Engelhard’s 15.4-liter ceramic monolith and Degussa’s lo-liter metal monolith. Typical emissions from ethanol-engine-with-catalyst in g/kW h are: NOx, 4.4; HC, 0.2; CO, 0.1; and particles, 0.05. For today’s “best bus”, the corresponding values are 9.0, 0.4, 0.6 and 0.3, Volume 90 No. 1 -
21 October 1992
respectively, and for today’s “typicalbus”, 16.0, 1.0, 1.5 and 0.6, respectively (see Reyden and Berg, in IX international Symposium on Alcohol Fuels, Florence, Italy, November 12-15,199l). The exhaust gases from the ethanol buses sometimes produced a slight smell of acetaldehyde and acetic acid (vinegar), causing some annoyance to cyclists and pedestrians on the road. This problem originated partly from a leaking fuel-line connection, which has now been rectified. To tackle this problem completely, research projects have been started jointly with catalysis research groups in universities and industries in Sweden. By June 1992, the buses in the test fleet had covered more than 80,009 km each in Stockholm city traffic. P.G. MENON
High-Temperature SCR Catalyst
Conventional catalysts for the selective catalytic reduction (SCR) of NOr require an operating temperature in the range 309 to 375°C. This necessitates splitting the heat recovery boiler into two sections to provide a space for the SCR catalyst in which the exhaust gas is at the required temperature. SCR catalysts that can operate at high temperature eliminate the need to split the heat recovery boiler. This results in reduced costs and simplified design of the heat recovery boiler. The high-temperature capability of an SCR catalyst is especially attractive for retrofitting existing cogeneration facilities where it is cost prohibitive to split an existing heat recovery boiler or to replace it with a new boiler. Norton’s NC-300 (TM) catalyst can be used for high-temperature operation. The applled catalysis A: General
NC-300 zeolite-based catalyst, with high silica/alumina ratio, is stable up to 565°C. The NC-399 catalyst is currently being used to remove NO, from gas turbine exhaust produced from a 3.9 MW gas turbine cogeneration facility at Unocal’s Science and Technology Division in Brea, CA (see Oil and Gas Journal, lBAprili992.) Unocal is the first to use the SCR process to reduce NOx emissions in high-temperature gas turbine exhaust operation. This system has been in continuous operation since December 1990 and has consistently met California’s strict regulations by maintaining outlet NOx emissions at less than 9 ppmv with an ammonia slip well below 29 ppmv as allowed by the air permit. The zeolite-based NC-309 catalyst offers some additional advantages over conventional V-Ti catalyst. The NC-300 catalyst is extruded into a homogeneous honeycomb structure which prevents operating problems due to thermal cycling and abrasion which can be detrimental to composite catalysts. The ion-exchanging capability of zeolites can control ammonia slippage. The strong resistance of zeolites to SOx allows operation with high sulfur fuels. The zeolite formulation in the NC-390 catalyst minimizes the disposal requirements. Furthermore, the conversion of SO2 to SOS is less than l%, thereby minlmizing the formation of ammonium salts that are detrimental to downstream equipment. SANJAY K. AGARWAL JAMES J. SPIVEY
Volume 90 No. 1 -
21 October 1992
nitride products on $21.9 million. The biggest application sector, ceramic wear parts, is set to grow from $218 million in 1991 to over $300 million in 1995. The highest growth rate, however, will be seen in the automotive catalyst support market, boosted by EC legislation on car exhaust emissions, which is expected to grow by over 18% to be worth $240 million in 1995. Legislation protecting against air pollution, already vigorously pursued in Germany, The Netherlands, Austria, Switzerland and Scandinavia has also boosted the catalyst supports market and even the industrial emissions sector, which experienced a large fall during 1990, is forecast year on year growth through to 1996. Within the automotive sector, several other ceramic applications are also expected to grow significantly up to 1995. “Although it is not unanimous,” Frost & Sullivan say, “it is expected that the use of silicon nitride parts and possibly valves in turbochargers may have become important in a series of production cars by 1995, with the lead given by German producers or UK-based Japanese producers.” The market for ceramic membranes, dominated by French producers in applications ranging from food and drink production to effluent cleaning, is expected to grow to more than double its present size by 1995. Other application sectors forecast to grow in coming years are cutting tools, bioceramics and molten metal filters used in high-temperature processes. The biggest national market is Germany due to lts high investment in pollution control technology and itsvery large dynamic mechanical and process engineering sectors. It is also the largest net exporter of engineering ceramics to other European countries. The
applied catalysis A: General
other main national markets are France, the UK and Italy. For further information, contact Nick Betts at Frost & Sullivan Ltd., Sullivan House, 4 Grosvenor Gardens, London SW1 OHD, UK, or Anne Gilroy at Frost & Sullivan Inc., 106 Fulton Street, New York, NY 10038, USA.
Ethanol-run Diesel Buses in Stockholm
A major road test has been going on for nearly two years in Stockholm city traffic with a fleet of 32 diesel buses run on ethanol. The aims of this test are: (a) to establish the real costs of operating a bus fleet on ethanol and to evaluate techniques and infm-structure; (b) to check exhaust emissions, both unregulated and regulated; and (c) to develop the engine system and produce a fuel specification. The ethanol (959/o,with 5% water) used is produced from a waste liquor from paper manufacture at a paper mill in the north of Sweden. A blend is made there of this ethanol (95%) MTBE as a denaturing agent (2%) and Avocet ignition enhancer (3%); this blended fuel is then transported by a truck to the bus depot, 700 km to the south. The Saab-Scania diesel bus engines have been modified, with the combustion chamber, compression, injection pressure, injection timing, etc., all adapted to the new fuel. The passenger load of the buses is 36 seated and 43 standing. The buses have been testing two exhaust catalysts: Engelhard’s 15.4-liter ceramic monolith and Degussa’s lo-liter metal monolith. Typical emissions from ethanol-engine-with-catalyst in g/kW h are: NOx, 4.4; HC, 0.2; CO, 0.1; and particles, 0.05. For today’s “best bus”, the corresponding values are 9.0, 0.4, 0.6 and 0.3, Volume 90 No. 1 -
21 October 1992
respectively, and for today’s “typicalbus”, 16.0, 1.0, 1.5 and 0.6, respectively (see Reyden and Berg, in IX international Symposium on Alcohol Fuels, Florence, Italy, November 12-15,199l). The exhaust gases from the ethanol buses sometimes produced a slight smell of acetaldehyde and acetic acid (vinegar), causing some annoyance to cyclists and pedestrians on the road. This problem originated partly from a leaking fuel-line connection, which has now been rectified. To tackle this problem completely, research projects have been started jointly with catalysis research groups in universities and industries in Sweden. By June 1992, the buses in the test fleet had covered more than 80,009 km each in Stockholm city traffic. P.G. MENON
High-Temperature SCR Catalyst
Conventional catalysts for the selective catalytic reduction (SCR) of NOr require an operating temperature in the range 309 to 375°C. This necessitates splitting the heat recovery boiler into two sections to provide a space for the SCR catalyst in which the exhaust gas is at the required temperature. SCR catalysts that can operate at high temperature eliminate the need to split the heat recovery boiler. This results in reduced costs and simplified design of the heat recovery boiler. The high-temperature capability of an SCR catalyst is especially attractive for retrofitting existing cogeneration facilities where it is cost prohibitive to split an existing heat recovery boiler or to replace it with a new boiler. Norton’s NC-300 (TM) catalyst can be used for high-temperature operation. The applled catalysis A: General
NC-300 zeolite-based catalyst, with high silica/alumina ratio, is stable up to 565°C. The NC-399 catalyst is currently being used to remove NO, from gas turbine exhaust produced from a 3.9 MW gas turbine cogeneration facility at Unocal’s Science and Technology Division in Brea, CA (see Oil and Gas Journal, lBAprili992.) Unocal is the first to use the SCR process to reduce NOx emissions in high-temperature gas turbine exhaust operation. This system has been in continuous operation since December 1990 and has consistently met California’s strict regulations by maintaining outlet NOx emissions at less than 9 ppmv with an ammonia slip well below 29 ppmv as allowed by the air permit. The zeolite-based NC-309 catalyst offers some additional advantages over conventional V-Ti catalyst. The NC-300 catalyst is extruded into a homogeneous honeycomb structure which prevents operating problems due to thermal cycling and abrasion which can be detrimental to composite catalysts. The ion-exchanging capability of zeolites can control ammonia slippage. The strong resistance of zeolites to SOx allows operation with high sulfur fuels. The zeolite formulation in the NC-390 catalyst minimizes the disposal requirements. Furthermore, the conversion of SO2 to SOS is less than l%, thereby minlmizing the formation of ammonium salts that are detrimental to downstream equipment. SANJAY K. AGARWAL JAMES J. SPIVEY
Volume 90 No. 1 -
21 October 1992